The 63 kg climber is supported in the "chimney" by the friction forces exerted on his shoes?

Question

and back. The static coefficients of friction between his shoes and the wall, and between his back and the wall, are 0.73 and 0.57, respectively. What is the minimum normal force he must exert? Assume the walls are vertical and that friction forces are both at a maximum. Ignore his grip on the rope.

Answer 1

First, from Newton's 3rd law we can assume the the same force (in opposite directions) is exerted on back and on shoes. Then all you do is add the friction coefficients.
Fn = mg/(0.73+0.57). It's up to the climber to distribute his weight between back and shoes in the same proportion.